In residential and commercial construction, a water heating system is necessary for heating water. However, water heating systems can be complex and inefficient. Known heating systems monitor characteristics about the water heating system to enhance the water heating system. Such characteristics may include monitoring the water temperature exiting the system, monitoring the rate at which gas enters the system, monitoring the amount of energy consumed in heating water, and the like. These heating systems are able to use such information to alter variables of the heating system in order to optimize the output of the system.
One characteristic that can be helpful in optimizing a heating system is the amount of oxygen in products of combustion in the heating system. Some heating systems are able to monitor the amount of oxygen in the products of combustion with non-dispersive Infrared (NDIR) sensors. NDIR sensors are spectroscopic devices often used for gas analysis. However, NDIR sensors are expensive and can cost approximately $30,000. Unfortunately, known heating systems have been unable to monitor the amount of oxygen combusted in the products of combustion effectively and in a cost efficient manner.